The present invention relates generally to a coupling device for mounting an implement on a tractor, which is preferably equipped with a belt drive. The coupling device includes coupling halves mounted on the implement side and tractor side. The coupling halves are movably connected to each other by several coupling rods.
The coupling device is sometimes referred to as a three-point linkage, which may comply with relevant standards. The coupling device usually includes two lower rods of the same height above the ground and an upper link arranged centrally thereabove. These coupling devices are designed for tractors with at least two driven wheels. Tractors of this kind have a relatively large turning radius due to the steering geometry of the axles. The coupling device makes it possible for the implement to be adjusted, or moved, laterally to a small extent in relation to the tractor. The need for adjustment is particularly necessary in the case of mounted machines or implements for soil cultivation. By means of the coupling device, cornering is possible to a limited extent for vehicles with a large turning radius, without overloading the elements of the coupling device when the mounted implement is in the lowered working position, for example, for soil cultivation.
Belt driven tractors, whose turning radius are clearly lower than those of tractors with steerable wheels, are being used to an increased extent because of their lower pressure load on the soil. Known coupling devices can be used only to a limited extent with belt-driven tractors because this type of tractor requires more lateral adjustment than known coupling devices can provide.
Cowley, European Patent No. 0 948 882 A1, discloses a coupling device which enables a steering function so that lateral forces transmitted to the tractor are reduced. For this purpose, the coupling device includes a rigid, central coupling rod about which are arranged three coupling rods, describing a triangle, which are adjustable in length. These coupling rods consist of hydraulic cylinders which on account of the central coupling rod must take up only relatively small forces. The piston rods of the hydraulic cylinder must be retracted and extended to change their length, which requires the hydraulic cylinders be controlled. This type of adjustment is however technically elaborate. It is therefore further proposed to use other coupling rods, which work on the linear drive principle, for example pneumatic actuators or recirculating-ball spindle actuators. The two mentioned examples are not normally considered for use in the agricultural sphere, because it would be necessary to furnish the tractors with a corresponding pneumatic or electrical system for these devices.
Defrancq, U.S. Pat. No. 5,092,409, describes a coupling device for front mounting of an implement. The connecting elements or coupling rods likewise consist of hydraulic cylinders, so that elaborate control is necessary.
Finally, Hune, German Patent No. 196 37 547 A1, discloses that the coupling halves can be connected by two pendulum supports in a V relative to each other. This solution is also technically elaborate, as it is necessary to adjust the pendulum supports by means of a motor-driven device in order for return to take place. A coupling device of this kind is not suitable for an agricultural implement because it is integrated in the power flux of a manipulator arm, so that one coupling half is attached to the manipulator arm, while the other coupling half for example carries a tool.
The present invention is directed to overcoming one or more of the problems set forth above.
An aspect of the invention is to provide a coupling device for connecting an implement to a tractor.
In another aspect of the invention there is provided a coupling device for connecting an implement to a tractor, wherein the coupling device has purely mechanical function.
In another aspect of the invention there is provided a mechanical coupling device for connecting an implement to a tractor, wherein the coupling device has a lower left and a lower right coupling rod, wherein each coupling rod has a lower front and a lower rear rod section, whereby the lower front rod section and the lower rear rod section are interlocked by resilient elements.
Yet another aspect of the invention is to provide a method for use of a coupling device for maintaining a mechanical connection between a tractor and an implement.
The above aspects are merely illustrative and should not be construed as all-inclusive. The aspects should not be construed as limiting the scope of the invention, rather the scope of the invention is detailed in the appended claims.